Bump sphinx from 3.3.1 to 3.5.3 (#711)

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 3.3.1 to 3.5.3.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/3.x/CHANGES)
- [Commits](https://github.com/sphinx-doc/sphinx/commits)

Signed-off-by: dependabot-preview[bot] <[email protected]>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Author: dependabot-preview[bot]

requirements_dev.txt

@@ -12,7 +12,7 @@ pytest-mock<3.5.2
 recommonmark==0.7.1
 requests==2.25.1
 requests-mock==1.8.0
-sphinx==3.3.1
+sphinx==3.5.3
 sphinx-rtd-theme==0.5.1
 tqdm==4.59.0
 websocket-client==0.58.0